Author Topic: Changing from SLA to LifePo4 batteries  (Read 17354 times)

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Offline Pete

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Re: Changing from SLA to LifePo4 batteries
« Reply #30 on: May 12, 2021, 07:41:44 pm »
Good luck Doc. Looks like a heavy battery bank. Pity there isn't a way to fit a pipe on the rafters so the chain block can't be slid along it. Hope it is a very long time before they need to be taken down
Pete

Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #31 on: May 12, 2021, 08:45:07 pm »
Thanks Pete,
Yeah, a set of two would be over 250lbs.  Good thing I removed two 20lb heatsinks from each module.  With the heatsinks they are said to weigh 168lbs per module.  Had to remove them for space considerations as well as weight.  It's a pretty tight fit as is.  Once they are in, I'm hoping it's the next owner of this house who will face taking them out!  ;)

Well, I got the first set of two onto the shelf.  Done for today.  I'm exhausted.

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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #32 on: May 14, 2021, 09:43:21 pm »

Finally got a chance to get the second set up onto the shelf.  Hauled 4 loads of firewood yesterday and a trip into Nampa today, but got them in!  Sadly, the first four were the easy ones.  Now I get to figure out how to get the next four on top of these four!  I do have a plan in mind but will it work?  The remaining four must be lifted into place one at a time, as I haven't got clearance to lift stacks of two that high.

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So, I next need to modify the lift cart, cut some wood spacers, and then we'll find out.
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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #33 on: May 19, 2021, 10:01:49 pm »
3rd set of two up.
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I know.  Looking at the picture, you're thinking, "What's the big deal?"
I spent several hours trying to get those two up there. I'm at the limit of my lifting range.  Had to modify the lift cart to get those up high enough.  Was off by an eighth of an inch.  They are too delicate to force-fit.  So more modifying. By the time I finally got everything to line up I had had the thing in the air 4 times and had to lower it back down and re-adjust.

Well, they are in.  Problem is, there are two more to go on top of those.  And the chainfall can't lift them high enough.  I do have a plan.  Tomorrow we'll see if it works.  Tonight I'm exhausted (and the chainfall did most of the work!).
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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #34 on: May 20, 2021, 03:37:22 pm »
Progress!
Lever top one from right hand stack up onto left hand stack.  Pain in the butt and took awhile but got it.

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Then lift another onto right hand stack;

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The last one is the b**ch!  Can't lift it high enough.
Going to have to build a ramp or platform as an intermediate step, then muscle it in.
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Offline Pete

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Re: Changing from SLA to LifePo4 batteries
« Reply #35 on: May 21, 2021, 12:01:23 am »
HI Doc it may be a bit late but if you use a piece of plywood as a ramp , and use pieces of dowling or old broom handles for rollers the battery packs will be easier to move into place.
I have used old wooden tent poles for rollers to get slow combustion stoves off a trailer up a ramp onto a house verandah and move them inside. Made the job pretty easy for me.
Pete

Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #36 on: May 23, 2021, 09:03:50 pm »

Hi Pete,
Thanks for the ideas.  Space is my limitation.  It's a real small area.  The other set of 8 let me use a ramp for the upper sets because it was a straight shot and I had my son-in-law to help me push them up the ramp.  This time it's just me and this set is in the corner.  Not a straight shot and stuff in the way so ramp won't work.
So, for this last module, I built an intermediate platform.

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Tomorrow I'll lift the module onto the platform with the chainfall.  Then lift one side and slide a 2x4 under, lift other side and slide another 2x4.  Keep doing that until the battery module is high enough to slide onto the stack.  Should work out ok.
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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #37 on: May 26, 2021, 04:39:27 pm »

I was uncertain a time or two, but it's in!  Hydraulic jacks are wonderful!
Put a crosspiece in, then used the jack to lift one side.  Put a 2x4 in.
Do the same on the other side.  Repeat until high enough, then push it onto the stack.
A little shaky towards the top but it's all good.  Relieved the heavy lifting is done.

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Now it's hookup time!
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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #38 on: May 26, 2021, 09:51:49 pm »
Each one of the byd modules had these two busbars, which I removed while removing the heatsinks, fans and such. So I have 8 of each type.

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One is a flat wide bar of what appears to be stainless steel.  I flattened out the bends to make one long flat piece and will use it to be the interconnect between the two 24v halves of the 48v bank.  With all cells paralleled, this one bar will make all the interconnects.  Might double up (use one on top of another)
The other one is 1/8" thick copper wrapped in black electrical tape.  Removed the tape and buffed off the copper.  Will use one as the positive and another as the negative busbar.  Might double them for 1/4" thick busbars.


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Tomorrow will drill the holes and bolt things up.  Then it's on to paralleling the cells.
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Offline Pete

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Re: Changing from SLA to LifePo4 batteries
« Reply #39 on: May 27, 2021, 01:35:04 am »
well done Doc, I hope for you that the batteries outlast you. May you never have to replace any of them.
What capacity do you have there in batteries now?
cheers
Pete

Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #40 on: May 27, 2021, 01:41:00 pm »

Thanks Pete,
The 48v bank is now 16 BYD modules (24v each).  They had a rating of 220ah when new.  That would make the bank rating 48v@1760ah if it was new.  So something less than that.  Maybe half?  880ah?
Should be more than adequate at any rate.
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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #41 on: May 29, 2021, 08:42:56 pm »
Got two of the three busbars made up and installed.  Used the wide flat bar for the interconnect between modules.  Turns out it is copper with a chrome plating.  Straightened out the bends, drilled a bunch of holes, stacked three to make it thick.
Used two stacked of the skinny copper bars, with the electrical tape removed and polished up some for the positive busbar.  Cut off the round post but left the side tabs at each end for extra connection points.
Now just have to do that again for the negative busbar.  Tomorrow hopefully.

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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #42 on: May 31, 2021, 05:23:43 pm »

Yesterday I made up and installed the negative busbar.  Today I've gotten most of the cells paralleled.  Had to quit for awhile. Doing wiring like that makes my back hurt and my eyes cross after awhile.  I'll finish up a bit later.  When I'm done the eight modules effectively become one huge 48v battery instead of 4 paralleled 48v batteries.

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Next will be mounting and wiring the shunt and active balancers.
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Offline dochubert

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Re: Changing from SLA to LifePo4 batteries
« Reply #43 on: June 03, 2021, 03:19:38 pm »

Got the 5a active balancer mounted and wired in last night.  The new set of modules is now connected to one of my 4 charge controllers and is charging up today.  When it's up to same voltage as the existing set, I'll make the parallel connection to put it in service.

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Still working on the shunt balancer setup.  More work and a little more complicated.  When it's all done the active balancer should handle things up to a point.  When a cell's voltage goes above the setpoint, the shunt blancer will kick in and bleed off excess the active balancer can't handle.  Due to the way it works the shunt balancer requires a sizable heatsink/fan setup to get rid of the heat from bleeding off excess power.
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Offline lighthunter

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Re: Changing from SLA to LifePo4 batteries
« Reply #44 on: June 13, 2021, 06:13:49 pm »
Looking good! You have quite an achievement there. Very massive storage. I dont reckon you will ever need more than you have now. Nice thing about LFP is the self discharge wont kill you like it does with very large mostly spent FLA.

You likely have your own preferences but i like to bottom balance cells so they all drop voltage at the same time when empty and terminate discharge when you hit 47.2 or 2.95vpc.  Then terminate the filling charge when the smallest capacity cell climbs over 3.5v.  active balancers depending on programming often shift charge levels at top and bottom throughout every cycle to eek the highest capacity. Its a cool idea in theory but it has limited value when considering wear and tear on cells and balancer.
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